1// RUN: %clang_tsan -O1 %s -o %t && %run %t 2>&1 | FileCheck %s 2 3// Test case for recursive signal handlers, adopted from: 4// https://code.google.com/p/thread-sanitizer/issues/detail?id=71 5 6#include "test.h" 7#include <semaphore.h> 8#include <signal.h> 9#include <errno.h> 10 11static const int kSigSuspend = SIGUSR1; 12static const int kSigRestart = SIGUSR2; 13 14static sem_t g_thread_suspend_ack_sem; 15 16static bool g_busy_thread_received_restart; 17 18static volatile bool g_busy_thread_garbage_collected; 19 20static void SaveRegistersInStack() { 21 // Mono walks thread stacks to detect unreferenced objects. 22 // If last object reference is kept in register the object will be collected 23 // This is why threads can't be suspended with something like pthread_suspend 24} 25 26static void fail(const char *what) { 27 fprintf(stderr, "FAILED: %s (errno=%d)\n", what, errno); 28 exit(1); 29} 30 31static void SuspendHandler(int sig) { 32 int old_errno = errno; 33 SaveRegistersInStack(); 34 35 // Enable kSigRestart handling, tsan disables signals around signal handlers. 36 sigset_t sigset; 37 sigemptyset(&sigset); 38 pthread_sigmask(SIG_SETMASK, &sigset, 0); 39 40 // Acknowledge that thread is saved and suspended 41 if (sem_post(&g_thread_suspend_ack_sem) != 0) 42 fail("sem_post failed"); 43 44 // Wait for wakeup signal. 45 while (!g_busy_thread_received_restart) 46 usleep(100); // wait for kSigRestart signal 47 48 // Acknowledge that thread restarted 49 if (sem_post(&g_thread_suspend_ack_sem) != 0) 50 fail("sem_post failed"); 51 52 g_busy_thread_garbage_collected = true; 53 54 errno = old_errno; 55} 56 57static void RestartHandler(int sig) { 58 g_busy_thread_received_restart = true; 59} 60 61static void StopWorld(pthread_t thread) { 62 if (pthread_kill(thread, kSigSuspend) != 0) 63 fail("pthread_kill failed"); 64 65 while (sem_wait(&g_thread_suspend_ack_sem) != 0) { 66 if (errno != EINTR) 67 fail("sem_wait failed"); 68 } 69} 70 71static void StartWorld(pthread_t thread) { 72 if (pthread_kill(thread, kSigRestart) != 0) 73 fail("pthread_kill failed"); 74 75 while (sem_wait(&g_thread_suspend_ack_sem) != 0) { 76 if (errno != EINTR) 77 fail("sem_wait failed"); 78 } 79} 80 81static void CollectGarbage(pthread_t thread) { 82 StopWorld(thread); 83 // Walk stacks 84 StartWorld(thread); 85} 86 87static void Init() { 88 if (sem_init(&g_thread_suspend_ack_sem, 0, 0) != 0) 89 fail("sem_init failed"); 90 91 struct sigaction act = {}; 92 act.sa_flags = SA_RESTART; 93 act.sa_handler = &SuspendHandler; 94 if (sigaction(kSigSuspend, &act, NULL) != 0) 95 fail("sigaction failed"); 96 act.sa_handler = &RestartHandler; 97 if (sigaction(kSigRestart, &act, NULL) != 0) 98 fail("sigaction failed"); 99} 100 101void* BusyThread(void *arg) { 102 (void)arg; 103 while (!g_busy_thread_garbage_collected) { 104 usleep(100); // Tsan deadlocks without these sleeps 105 } 106 return NULL; 107} 108 109int main(int argc, const char *argv[]) { 110 Init(); 111 pthread_t busy_thread; 112 if (pthread_create(&busy_thread, NULL, &BusyThread, NULL) != 0) 113 fail("pthread_create failed"); 114 CollectGarbage(busy_thread); 115 if (pthread_join(busy_thread, 0) != 0) 116 fail("pthread_join failed"); 117 fprintf(stderr, "DONE\n"); 118 return 0; 119} 120 121// CHECK-NOT: FAILED 122// CHECK-NOT: ThreadSanitizer CHECK failed 123// CHECK-NOT: WARNING: ThreadSanitizer: 124// CHECK: DONE 125